<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>06_盒子模型外间距</title>
    <style>
        /* 选中所有元素去除自带的内外间距*/
        *{
            margin: 0;
            padding: 0;
        }
        .fu>.zi {
            width: 100px;
            height: 100px;
            background-color: rgba(0,0,255,.5);
            border: 5px red solid;
        }
    </style>
</head>
<body>
<!--.fu>.zi*4+TAB表示创建父子双层结构的div元素，一个父四个子-->
<div class="fu">
    <div class="zi">111</div>
    <div class="zi">222</div>
    <div class="zi">333</div>
    <div class="zi">444</div>
</div>
</body>
</html>